Norwegian here: While building their house, my grandparents had (by law) to build the basement solid enough to be used as a bomb shelter, this was in the fiftie

Norwegian here: While building their house, my grandparents had (by law) to build the basement solid enough to be used as a bomb shelter, this was in the fifties i believe. I now live in an apartment block from early sixties and every block here (with around 24 apartments) has their own bomb shelter in the basement. Even some of our subway stations are (rather large) bomb shelters. In my home village, both some of the schools and sport facilities all had their own bomb shelters which also had facilities for keeping gas out. I do believe that is no longer required to build new bomb shelters but all existing ones has to be maintained and be ready to be used within a specified timeframe.